Process for treating mineral coating agent and binder compositions with plastics

ABSTRACT

PCT No. PCT/EP96/04999 Sec. 371 Date May 13, 1998 Sec. 102(e) Date May 13, 1998 PCT Filed Nov. 14, 1996 PCT Pub. No. WO97/18175 PCT Pub. Date May 22, 1997A process is provided for treating mineral hydraulically or non-hydraulically setting coating agent and binder compositions using water-redispersible powders wherein one or more organopolymer powders and one or more organosilicon powders are added to the dry coating agent and binder composition.

BACKGROUND OF THE INVENTION

1) Field of the Invention

The invention relates to a process for the polymer modification ofmineral coating agent and binder compositions by means of powders whichare redispersible in water.

2) Background Art

The modification of powder paints, hydraulically setting systems, suchas cementitious systems, gypsum-containing compositions and otherpulverulent building materials by polymers which are redispersible inwater is described in the prior art. The polymeric substances addedusually act as binders. They often increase the elasticity and reducethe brittleness of the materials.

EP-A 149098 (U.S. Pat. No. 4,859,751) discloses, for example,redispersible powders based on vinyl chloride/ethylene copolymers asadditives in hydraulic compositions, paints and coating compositions,adhesives and plastic plasters, to improve their mechanical properties.EP-A 407889 describes the use of redispersible polymer powders asadditives for hydraulic binders to improve the mechanical strength. DE-A4317036 describes polymer powders based on methyl methacrylate asadditives in mineral binding building materials.

It is furthermore known from the prior art to employ organosiliconcompounds, such as polysiloxanes or organosilanes, in powder form forhydrophobizing powder paints, hydraulically setting building materialsor other pulverulent building materials. EP-A 228657 describesredispersible organosilicon compounds as hydrophobizing additives toplasters, hydraulic binders or paints. EP-A 508155 describespolysiloxane powders as hydrophobizing agents. EP-A 279373 disclosesredispersible organopolysiloxane powders as additives in buildingmaterials.

Although these products are suitable as hydrophobizing agents, interalia, for hydraulically setting compositions, their binder character isin general less pronounced than that of organic polymers. In addition,the use of organosilicon compounds as binders for application inbuilding materials comprising mineral coating agent and bindercompositions is often prohibited in practice for economic reasons and/orowing to considerations of performance, since if excessive amounts areadded the processing properties are adversely affected.

In certain uses for mineral coating agent and binder compositions, ahydrophobizing effect is now also required, in addition to improvedmechanical properties. It is known from the prior art to employ for thispurpose dispersible powders which are obtained by spray drying anaqueous mixture of vinyl polymer or acrylic polymer and silicone (EP-A493168) or are obtained by spray drying an aqueous mixture of organicpolymer and organosilicon compound (DE-A 4402409).

Depending on the amount and types of organosilicon compounds(s) added tothe aqueous mixture to be dried, binders which are hydrophobizing to agreater or lesser degree can thus be prepared. It is a significantdisadvantage here that the requirements placed on such additives differgreatly, and for this reason a specific redispersible powder with aspecific organic polymer/organosilicone mixing ratio must be preparedfor each requirement, which results in a large number of different typesof product. Co-spraying organic polymer dispersions with organosiliconeemulsions which are incompatible with them, for example because ofincompatible emulsifier/protective colloid systems, is also problematic.

The object was therefore to provide a process for modifying mineralcoating agent and binder compositions with organic polymers andorganosilicon compounds which ensures a higher flexibility in respect ofthe ratios of amounts of organic polymer and organosilicon content,compared with the prior art, and avoids the abovementionedincompatibilities.

SUMMARY OF THE INVENTION

The invention relates to a process for the polymer modification ofmineral coating agent and binder compositions, which are hydraulicallysetting or are not hydraulically setting, by means of powders which areredispersible in water, characterized in that one or more organicpolymer powders which are redispersible in water and one or moreorganosilicon powders which are redispersible in water are added to thedry coating or binder composition.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The mineral, hydraulically setting coating agent and binder compositionsare those based on hydraulic binders, such as cement and gypsum. Thesecompositions usually also comprise additives: for example pigments, suchas titanium oxide, fillers, such as talc, quartz (sand), calciumcarbonate, aluminum silicates or fiber materials, thickeners, such ascellulose, dispersants, fungicides, preservatives, defoamers, wettingagents or film formation auxiliaries. Such binder and coatingcompositions are used as cement mortars, plasters, building adhesives(for example the adhesives), filling and stopping compositions orplaster of Paris. The corresponding recipes are known to the expert.

The mineral coating agent and binder compositions which are nothydraulically setting are compositions which comprise mineral fillers,such as titanium oxide, calcium carbonate, kaolins or barium sulfate,and which usually comprise synthetic resins as binders. In the procedureaccording to the invention, the synthetic resin content can beintroduced as a whole by means of the redispersible organic polymer;alternatively, the redispersible organic polymer can be introduced inaddition to the synthetic resin content. These compositions usually alsocomprise additives: for example pigments, thickeners, such as cellulose,dispersants, fungicides, preserving auxiliaries, defoamers, wettingagents or film formation auxiliaries. Such binder and coatingcompositions are employed as paints, primers, cement-free stoppingcompositions, coating agents for paper and textiles and as adhesives forwood, paper and plastic. The corresponding recipes are known to theexpert.

The amount of organic polymer powder and organo-silicon powder addeddepends greatly on the particular use for which the coating agent orbinder composition is intended. The content of organic polymer powder isusually considerably higher than the content of organosilicon powder.0.1 to 20% by weight of one or more redispersible organic polymerpowders and 0.001 to 5.0% by weight of one or more organosilicon powderswhich are redispersible in water are usually added to the dry coatingagent or binder composition, in each case based on the dry weight of thecoating agent or binder compositions.

In the procedure according to the invention, the organic polymer powderand the organosilicon powder are mixed with the dry formulationconstituents of the coating agent and binder compositions. The additionto the formulation constituents can be carried out here separately or asa ready-made mixture of organic polymer and organosilicon powder in theusual equipment for dry mixing. The coating and binder compositions arethen rendered ready to process, if appropriate after addition of waterand other, possibly liquid, additives.

The organic polymer powders which are redispersible in water areprepared by drying a dispersion of a water-insoluble polymer in asolution, which is in general aqueous, of a film-forming, water-solublepolymer, if appropriate in the presence of further additives, such as,for example, emulsifiers, antiblocking agents, biocides, plasticizers,film formation auxiliaries, foam stabilizers or defoamers. Thedispersions to be dried in general have a solids content of 20 to 60%.Drying is preferably carried out by spray drying in a hot stream of airand/or stream of inert gas. It can also be carried out by freeze dryingand, if the polymers are water-insoluble polymers which do not form afilm under the drying conditions applied, also by thin film drying, forexample belt drying or roller drying.

Preferred water-insoluble polymers are: Vinyl ester homo- or copolymerscomprising one or more monomer units from the group consisting of vinylesters of unbranched or branched alkylcarboxylic acids having 1 to 15 Catoms;

(Meth)acrylic acid ester homo- or copolymers comprising one or moremonomer units from the group consisting of methacrylic, acid esters andacrylic acid esters of unbranched or branched alcohols having 1 to 12 Catoms; Homo- or copolymers of fumaric and/or maleic acid mono- ordiesters of unbranched or branched alcohols having 1 to 12 C atoms;

Homo- or copolymers of dienes, such as butadiene or isoprene, and ofolefins, such as ethene or propene, it being possible for the dienen tobe copolymerized, for is example with styrene, (meth)acrylic acid estersor the esters of fumaric or maleic acid;

Homo- or copolymers of vinyl aromatics, such as styrene, methylstyreneor vinyltoluene; and

Homo- or copolymers of vinyl-halogen compounds, such as vinyl chloride.

Preferred vinyl esters are vinyl acetate, vinyl propionate, vinylbutyrate, vinyl 2-ethylhexanoate, vinyl laurate, 1-methylvinyl acetate,vinyl pivalate and vinyl esters of α-branched monocarboxylic acidshaving up to 10 C atoms, for example those having 9 to 10 C atoms (soldby the Shell Corporation under trademarks (VeoVa 9® or VEDVA®), andvinyl methylnorbornanemonocarboxylate. Vinyl acetate is particularlypreferred.

Preferred methacrylic acid esters or acrylic acid esters are methylacrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate,propyl acrylate, propyl methacrylate, n-butyl acrylate, t-butylacrylate, n-butyl methacrylate, t-butyl methacrylate and 2-ethylhexylacrylate. Methyl acrylate, methyl methacrylate, n-butyl acrylate and2-ethylhexyl acrylate are particularly preferred. Preferred ester groupsof fumaric, and maleic acid are the methyl, ethyl, n-propyl, iso-propyl,n-butyl, iso-butyl, t-butyl, hexyl, ethylhexyl and dodecyl group.

If appropriate, the vinyl ester copolymers can comprise 1.0 to 65% byweight, based on the total weight of the comonomer phase, of α-olefins,such as ethylene or propylene, and/or vinyl aromatics, such as styrene,and/or vinyl halides, such as vinyl chloride, and/or acrylic acid estersor methacrylic acid esters of alcohols having 1 to 10 C atoms, such asmethyl acrylate, methyl methacrylate, ethyl acrylate, ethylmethacrylate, propyl acrylate, propyl methacrylate, n-butyl acrylate,t-butyl acrylate, n-butyl methacrylate, t-butyl methacrylate and2-ethylhexyl acrylate, and/or ethylenically unsaturated dicarboxylicacid esters or derivatives thereof, such as diisopropyl fumarate and thedimethyl, methyl t-butyl, di-n-butyl, di-t-butyl and diethyl esters ofmaleic, acid and fumaric acid, or maleic anhydride. If appropriate, the(meth)acrylic acid ester copolymers can comprise 1.0 to 65% by weight,based on the total weight of the comonomer phase, of α-olefins, such asethylene or propylene, and/or vinyl aromatics, such as styrene, and/orvinyl halides, such as vinyl chloride, and/or ethylenically unsaturateddicarboxylic acid esters or derivatives thereof, such as diisopropylfumarate and the dimethyl, methyl butyl, dibutyl and diethyl esters ofmaleic acid and fumaric acid, or maleic anhydride.

In a preferred embodiment, the vinyl, ester copolymers and the(meth)acrylic acid ester copolymers also comprise 0.05 to 10.0% byweight, based on the total weight of the comonomer mixture, of auxiliarymonomers from the group consisting of ethylenically unsaturatedcarboxylic acids, preferably acrylic acid or methacrylic acid; from thegroup consisting of ethylenically unsaturated carboxylic acid amides,preferably acrylamide; from the group consisting of ethylenicallyunsaturated sulfphonic acids or salts thereof, preferably vinylsulphonicacid; and/or from the group consisting of polyethylenically unsaturatedcomonomers, for example divinyl adipate, diallyl maleate, allylmethacrylate or triallyl cyanurate. Comonomers which have a crosslinkingaction are also suitable as auxiliary monomers, for exampleacrylamidoglycolic acid (AGA), methylacrylamidoglycolic acid methylester (MAGME), N-methylolacrylamide (NMAA), N-methylolmethacrylamide,allyl N-methylolcarbamate and alkyl ethers, such as the isobutoxy ether,or esters of N-methylolmethacrylamide or of allyl N-methylolcarbamate.

Statements corresponding to those for the (meth)acrylic acid estercopolymers apply to the copolymers of the esters of maleic or fumaricacid.

In a preferred embodiment, the dispersible powder composition comprises8 to 60% by weight, preferably 10 to 35% by weight, of protectivecolloid, based on the total amount of water-insoluble polymer, some ofthe amount of protective colloid preferably being added to the finished,dispersion or the solution or mixture of the composition of polymer andfurther additives before spray drying, preferably in the form of anaqueous solution. Suitable protective colloids are, for example,polyvinyl alcohols and derivatives thereof; polysaccharides inwater-soluble form, such as starches (amylose and amylopectin),cellulose, guar, tragacanthic acid, dextran, alginates andcarboxymethyl, methyl, hydroxyethyl and hydroxypropyl derivativesthereof; proteins, such as casein, soya protein and gelatine; syntheticpolymers, such as poly(meth)acrylic acid, poly(meth)acrylamide,polyvinylsulphonic acids and water-soluble copolymers thereof;melamine-formaldehydesulphonates, naphthaleneformaldehydesulphonates andstyrene/maleic acid and vinyl ether/maleic acid copolymers.

Additives which are in solid, preferably pulverulent, form can also beadded to the redispersible powder during or after drying, such as, inparticular, antiblocking agents, such as Ca carbonate or Mg carbonate,talc, gypsum, silicic acid, silicates, aluminum oxide and pigments, ineach case with particle sizes preferably in the range from 5 nm to 10μm.

The silicon compounds which are redispersible in water can be preparedby drying emulsions and/or dispersions of organosilicon compounds whichare insoluble in water and preferably boil at >160° C. Theemulsification of organosilicon compounds which are solid at roomtemperature can be carried out either under the influence of heat or byprior dissolution in a suitable organic solvent or by mixing with one ormore other (organo)silicon compound(s) which are preferably liquid atroom temperature, in an aqueous solution of film-forming polymers, ifappropriate in the presence of emulsifiers, antiblocking agents andother additives. Drying or microencapsulation can be carried out byspray drying, freeze drying or thin film drying, such as belt drying orroller drying.

Preferred organosilicon compounds which are redispersible in water are:silicic acid esters Si(OR')₄, organoorganoxysilanes SiR_(n) (OR')_(4-n),where n=1 to 3, polysilanes of the general formula R₃ Si(SiR₂)_(n) SiR₃,where n=0 to 500, preferably 0 to 8, di-, oligo- and polysiloxanes ofunits of the general formula R_(c) H_(d) Si(OR')_(e) (OH)_(f)O.sub.(4-c-e-e-f)/2, where c=0 to 3, d=0 to 1, e=0 to 3, f=0 to 3 andthe sum c+d+e+f is not more than 3.5 per unit, in which R' is identicalor different alkyl radicals or alkoxyalkylene radicals having 1 to 4 Catoms, preferably methyl or ethyl, and R is identical or different andis branched or unbranched alkyl radicals having 1 to 22 C atoms,cycloalkyl radicals having 3 to 10 C atoms, alkylene radicals having 2to 4 C atoms or aryl, aralkyl or alkylaryl radicals having 6 to 18 Catoms, where the radicals R mentioned can also be substituted byhalogens, such as F or Cl, or by ether, thioether, ester, amide,nitrile, hydroxyl, amine, carboxyl, sulphonic acid, carboxylic acidanhydride and carbonyl groups, and where, in the case of thepolysilanes, R can also have the meaning OR'.

Particularly preferred organosilicon compounds are: tetraethoxysilane,methyltripropoxysilane, methyltriethoxysilane,γ-chloropropyltriethoxysilane, β-nitriloethyltriethoxysilane,γ-mercaptopropyltriethoxy- and -trimethoxysilane, phenyltriethoxysilane,iso-octyltriethoxysilane, dipropyldiethoxysilane, triphenylsilanol andcondensation products, which are preferably liquid, thereof, ifappropriate with other low-boiling and/or water-soluble silanes, such asmethyltrimethoxysilane, γ-aminopropyltriethoxysilane or other silanescontaining amino functions, silanes containing quaternary ammonium saltgroups, silanes containing epoxide groups, and silanes containingcarboxylic acid or carboxylic acid anhydride functional groups. Thedisilanes dimethyltetraalkoxydisilane, tetramethyldialkoxydisilane,trimethyltrialkoxydisilane or (co)condensates thereof which aregenerally obtainable from the corresponding chlorine compounds.Methylhydridopolysiloxanes blocked by trimethylsiloxy end groups,copolymers of dimethylsiloxane and methylhydridosiloxane units blockedby trimethylsiloxy end groups and dimethylpolysiloxanes which contain anSi-bonded hydroxyl group in each of the terminal units are alsoparticularly preferred.

The preparation of the organosilicon compounds can be carried out byprocesses such as are described in Noll, Chemie und Technologie derSilicone [Chemistry and Technology of the Silicones], 2nd Edition 1968,Weinheim and in Houben-Weyl, Methoden der organischen Chemie [Methods oforganic Chemistry], Volume E 20, page 1782 f 2219 f, Georg ThiemeVerlag, Stuttgart, 1987.

If powders with poorer redispersing properties are to be added, forexample in order to achieve a delayed development of the action, thosewhich comprise at least, as an additional protective colloid, ammoniumsalts of copolymers of styrene and maleic and/or fumaric acid, ofcondensation products of sulphonated phenols or naphthalenes withformaldehyde, or of other film-forming polymers which are water-solublebecause of the ammonium salt groups, are preferably used. Water-solubleproteins which keratinize under the preparation or use conditions arealso suitable for this purpose.

The organosilicon compounds described and (organo)silicon compoundswhich are water-soluble and also boil at <150° C. can also be added tothe building material mixture in a form applied to a carrier substance.In this case, they are applied to a preferably pulverulent carriersubstance. The preparation of such compositions of organosiliconcompounds applied to carrier substances is described in DE-A 19535833.

The particle size of the pulverulent, inorganic or organic carriersubstances is preferably from 0.005 to 3000 μm, in particular up to 500μm. Suitable carrier substances which have an adsorptive action arepreferably finely divided solids having the largest possible BET surfacearea, preferably >5 m² /g, particularly preferably >10 m² /g.

Examples of carrier substances which have an adsorbtive action and/orinclude the liquids in their pores are precipitated chalk and otherfinely divided carbonates, such as magnesium carbonate and/or calciumcarbonate, as well as magnesium hydrosilicates, finely divided titaniumdioxide, aluminas, bleaching earths, activated aluminium oxide,vermiculites, such as bentonite, expanded perlite and phosphates, suchas Na phosphate. Crosslinked and non-crosslinked organic materials arealso suitable, such as, for example, polyvinyl alcohol powder;pulverulent cellulose (derivatives); pulverulent starch (derivatives);polyvinyl chloride powders; rubbers and thermosetting resins.

The mineral, hydraulically setting coating agent and binder compositionsprepared according to the invention are suitable for use as cementmortars, plasters, building adhesives (for example the adhesives),filling or stopping compositions or plaster of Paris. For thesepurposes, the additives customary in these applications can also beadded to the compositions, for example pigments, such as titanium oxide,fillers, such as talc, quartz (sand), calcium carbonate, aluminiumsilicates or fibre materials, thickeners, such as cellulose,dispersants, fungicides, preserving auxiliaries, defoamers, wettingagents or film formation auxiliaries.

The mineral coating agent and binder compositions prepared according tothe invention which are not hydraulically setting are suitable for useas paints, primers, cement-free stopping compositions, coating agentsfor paper and textiles and as adhesives for wood, paper and plastic. Forthese purposes, the additives customary in these applications can alsobe added to the compositions, for example pigments, thickeners, such ascellulose, dispersants, fungicides, preserving auxiliaries, defoamers,wetting agents or film formation auxiliaries.

The procedure according to the invention offers the following advantagesover the prior art: The material to be conditioned can be optimized,according to application technology requirements, with few products, ingeneral two being sufficient (a redispersible organic polymer and aredispersible organosilicon compound), in the desired ratio of amountsaccording to the profile of requirements. In contrast to the prior art,with a fixed given organic polymer/organosilicon ratio in theredispersible powder, this leads to considerable savings in costs bothfor the producer of these conditioning products and for the producer ofthe coating or building binder dry mixtures which are hydraulicallysetting or are not hydraulically setting: the need to store and processmany different organic polymer/organosilicone dispersible powders withfixed given ratios is eliminated.

The reason for using the previously known dispersible powders with afixed given organic polymer/organosilicone ratio was that with the verysmall amount usually used of organosilicone compound, it could not beexpected that these small amounts would be able to be admixedhomogeneously to coating or binder compositions. The prior art thereforetook the path of spraying aqueous dispersions of high organic polymercontent and low organosilicone content in order to distribute theorganosilicone content homogeneously over the higher organic polymercontent. It is surprising in the case of the procedure according to theinvention that the relatively very small amounts of organosiliconcompounds mixed in have just as good an effect, in spite of adistribution which is certainly not optimum, as when they areincorporated via the considerably larger amount of organicpolymer/organosilicon dispersible powder.

EXAMPLES Examples 1-4

    ______________________________________                                        Joint filler recipe:                                                          ______________________________________                                        300.0  parts    of Portland cement PZ 35 F                                    40.0   parts    of aluminate cement (HAC-Fondu Lafarge)                       649.5  parts    of quartz sand (0.1-0.4 mm)                                   0.5    parts    of Culminal C 8556                                            10.0   parts    of dispersible powder (see Table 1)                           X      parts    of isooctyltriethoxysilane powder (IOTES                                      powder), microencapsulated with 14% of                                        polyvinyl alcohol                                             200    ml       of water per 1000 g of dry mixture                            ______________________________________                                    

Testing of the joint filler recipe

The flexural tensile strength and compressive strength of cementcompositions prepared with these recipes were tested in accordance withDIN 1164. The uptake of water was determined in accordance with DIN52617. The samples were stored for 14 days in a standard climate (23°C./50% relative atmospheric humidity). The processibility was evaluatedqualitatively.

The results of the testing are summarized in Table 1.

                                      TABLE 1                                     __________________________________________________________________________                       Comparison                                                                          Comparison      Comparison                           Example No.                                                                            1    2    Example 1                                                                           Example 2                                                                           3    4    Example 3                            __________________________________________________________________________    Uptake of water                                                                        0.25 0.15  0.79  0.24 0.16 0.12  0.58                                (kg/m.sup.2 · h.sup.0.5)                                             Flexural tensile                                                                       4.7  4.5  4.9   4.8   4.7  5.5  5.6                                  strength (N/mm.sup.2)                                                         Compressive                                                                            16.8 16.2 17.3  17.0  16.7 18.2 18.4                                 strength (N/mm.sup.2)                                                         Processibility                                                                         Somewhat                                                                           Somewhat                                                                           Somewhat                                                                            Somewhat                                                                            Somewhat                                                                           Very Very good                                     tacky                                                                              tacky                                                                              tacky tacky tacky                                                                              good                                      Dispersible powder                                                                     RE545Z**                                                                           RE545Z**                                                                           RE545Z**                                                                            *     *    LL512***                                                                           LL512***                             type                                                                          Parts of IOTES                                                                         0.29 0.44 --    --    0.15 0.44 --                                   powder                                                                        __________________________________________________________________________     *As RE 545 Z with 0.25%, based on the polymer, of cosprayed                   isooctyltriethoxysilane                                                       **Product of WackerChemie GmbH, redispersible vinyl acetate/ethylene          powder                                                                        ***Product of WackerChemie GmbH, redispersible styrene/butyl acrylate         powder                                                                   

The test results in Table 1 show that the compositions preparedaccording to the invention have the same hydrophobizing action, with thesame amount of silane added, as products of the correspondinglyhydrophobized redispersible polymer powders (Example 1 and ComparisonExample 2). Comparison Example 1 shows the values which are obtainedwithout addition of silane.

Compared with Comparison Example 2, Examples 2 and 3 show that thehydrophobizing action of dispersible powders which have already beenhydrophobized can be improved by this process. These experiments alsoshow that there is no significant difference in respect of mechanicalstrength and hydrophobizing action between incorporation of thehydrophobizing agent into the redispersible polymer powder, which is inthis case already hydrophobized, and separate mixing of the entirehydrophobizing agent into the building material mixture.

Example 4 and Comparison Example 3 demonstrate corresponding results inthe case where another type of resin is used.

Example 5

    ______________________________________                                        Full thermal insulation recipe (building adhesive):                           ______________________________________                                        280.0  parts    of Dykerhoff white cement                                     500.0  parts    of quartz sand (0.1-0.4 mm)                                   190.0  parts    of Juraperle MHS                                              1.5    parts    of Tylose BA 2741                                             20.0   parts    of dispersible powder (see Table 2)                           X      parts    of isooctyltriethoxysilane powder, micro-                                     encapsulated with 14% of polyvinyl alcohol                                    (IOTES powder)                                                20.0   parts    of water                                                      ______________________________________                                    

Testing of the building adhesive recipe:

The tensile bond strength was determined at a peel-off rate of 250 N/safter storage in the dry state for 14 days. For the water drop test, 0.5ml of water was applied with a pipette to the surface of the adhesivecomposition applied to Styropor, and the time taken for the drop to beabsorbed was measured.

                  TABLE 2                                                         ______________________________________                                        (Testing of the adhesive recipe on polystyrene sheets)                                                         Comparison                                   Example  5           6           Example 4                                    ______________________________________                                        Tensile bond                                                                           0.1         0.1         0.1                                          strength 100% Styropor                                                                             100% Styropor                                                                             70% Styropor                                 (N/mm.sup.2)                                                                           torn out    torn out    torn out                                     Water drop                                                                             140 minutes 360 minutes 5 minutes                                    test                                                                          Dispersible                                                                            RE 545 Z    RE 545 Z    RE 545 Z                                     powder type                                                                   Parts of IOTES                                                                         0.29        0.44                                                     powder                                                                        ______________________________________                                    

The results show that the hydrophobizing properties of this buildingadhesive can be varied within wide limits with the process claimed.

Example 7

    ______________________________________                                        Rolling plaster recipe:                                                       ______________________________________                                        452.0   parts     of Inducarb 500 (CaCO.sub.3, 0.03-0.5 mm)                   200.0   parts     of Inducarb 0000 (CaCO.sub.3, 0.4-0.9 mm)                   150.0   parts     of white cement PZ 45 F                                     80.0    parts     of hydrated lime 2741                                       40.0    parts     of Kronos 2056 (TiO.sub.2 pigment)                          15.0    parts     of Arbocel BC 1000 (cellulose ether)                        2.0     parts     of Culminal MC 3000 PR (cellulose ether)                    1.0     part      of Amylotex 8100 (starch ether)                             60.0    parts     of dispersible powder                                       X       parts     of isooctyltriethoxysilane powder, partly                                     condensed, microencapsulated with 14% of                                      polyvinyl alcohol (IOTES powder)                            Water requirement per 1000 g of dry mixture: about 350 ml                     ______________________________________                                    

Testing of the roller powder recipe:

The tensile bond strength of plasters prepared with these recipes wastested in accordance with DIN 1164.

With method A, the measurement was carried out after storage in the drystate for 28 days at 23° C./50% relative atmospheric humidity. Withmethod B, the measurement was carried out after storage in the dry statefor 7 days at 23° C./50% relative atmospheric humidity and storage for afurther 21 days under water at 23° C. The flexural tensile strength andcompressive strength, were determined in accordance with theabovementioned standard after storage in the dry state for 28 days at23° C/50% relative atmospheric humidity.

The water uptake coefficient was determined in accordance with DIN 52617after storage of the recipe in the dry state for 14 days at 23° C./50%relative atmospheric humidity.

The results of the testing are summarized in Table 3.

                  TABLE 3                                                         ______________________________________                                                                                   Com-                                                                   Com-   parison                                                                parison                                                                              Exam-                              Example 7       8       9     10    Example 5                                                                            ple 6                              ______________________________________                                        Tensile bond                                                                  strength                                                                      Method A                                                                              0.84    0.92    0.79  0.81  0.80   0.68                               (N/mm.sup.2)                                                                  Method B                                                                              0.91    0.87    0.69  0.72  0.81   0.71                               (N/mm.sup.2)                                                                  Compressive                                                                           3.42    3.05    2.77  3.21  3.18   2.59                               strength                                                                      (N/mm.sup.2)                                                                  Flexural ten-                                                                         2.53    2.39    2.34  2.60  2.57   2.28                               sile                                                                          strength                                                                      (N/mm.sup.2)                                                                  Water uptake                                                                          0.152   0.071   0.057 0.091 0.070  0.362                              (kg/m.sup.2 · h.sup.0.5)                                             Dispersible                                                                           RE545Z  RE545Z  RE545Z                                                                              RE545Z                                                                              *      RE545Z                             powder                                                                        type                                                                          Parts of                                                                              0.29    0.44    0.6   --    --     --                                 IOTES                                                                         powder                                                                        Parts of                                                                              --      --      --    0.44  --     --                                 IOTES/                                                                        Trasil                                                                        powder                                                                        (1:2)**                                                                       ______________________________________                                         *= As RE 545 Z with 0.25%, based on the polymer, of cosprayed                 isooctyltriethoxysilane                                                       **Trasil is a partly condensed methyltrimethoxysilane (product of             WackerChemie GmbH)                                                       

Table 3 shows that the same hydrophobizing action is achieved with theprocess described as with the known processes, but with the advantagethat the hydrophobization can be varied according to the requirements ofthe user.

Examples 11-12

Alabaster gypsum mortar was modified with in each case 2% of dispersiblepowder, 1% of hydrated lime and optionally X % of microencapsulatedsiloxane powder (81% strength) (water/gypsum: 0.65)

The tests were carried out on 1×4×16 cm³ prisims after the followingstorage:

    ______________________________________                                        1 day              in the shuttering                                          5 days             standard climate                                           5 days             40° C.                                              1 day              standard climate                                           ______________________________________                                    

After this storage the samples had reached constant weight and werehydrated completely to the dihydrate.

The capillary uptake of water can be seen from Table 4.

                  TABLE 4                                                         ______________________________________                                                                          Comparison                                  Example       11        12        Example 7                                   ______________________________________                                        Dispersion powder type                                                                      RE524Z**  RE524Z**  RE524Z**                                    H-siloxane powder (81%                                                                      0.074*    --        --                                          strength)***                                                                  Trasil powder****                                                                           --        0.6*      --                                          Capillary uptake of water,                                                    rise in cm after                                                              1 hour        0.7       0.5       5.3                                         3 hours       1.6       1.2       10.6                                        24 hours      7.1       5.6       saturated                                   ______________________________________                                         *Based on the total mixture                                                   **Product of WackerChemie GmbH, VAc/E copolymer powder stabilized with        polyvinyl alcohol                                                             ***Hsiloxane powder microencapsulated with 19% of polyvinyl alcohol           ****Product of WackerChemie GmbH, partly condensed methyltriethoxysilane,     microencapsulated with 19% of polyvinyl alcohol                          

What is claimed is:
 1. Process for the polymer modification of mineralcoating agent and binder compositions, which are hydraulically settingor are not hydraulically setting, which comprises adding to the coatingagent or composition one or more organic polymer powders which areredispersible in water and one or more organosilicon powders which areredispersible in water to the dry coating or binder composition. 2.Process according to claim 1, wherein 0.1 to 20% by weight of one ormore redispersible organic polymer powders and 0.001 to 5.0% by weightof one or more organosilicon powders which are redispersible in waterare added to the dry coating agent or binder composition, in each casebased on the dry weight of the coating agent or binder compositions. 3.Process according to claim 1, wherein the organic polymer powder and theorganosilicon powder are added separately.
 4. Process according to claim1, wherein the organic polymer powder and the organosilicon powder areadded as a ready-made mixture of organic polymer and organosiliconpowder.
 5. A mineral coating agent which has been modified by theprocess of claim
 1. 6. A binding composition which has been modified bythe process of claim 1.